Children with Attention-Deficit/Hyperactivity Disorder (ADHD) participated in double-blind placebo-controlled randomized trails of stimulants while undergoing anatomic imaging with magnetic resonance imaging (MRI). The four approached are (1) anatomic imaging with magnetic resonance imaging, (2) neuropharmacology, (3) genetic studies, and (4) neurophysiological investigations. In anatomic studies, girls with ADHD have shown similar basal ganglia and prefrontal brain abnormalities to those seen in our previous study of boys. Subjects also participate in a longitudinal study of brain development. An on going follow-up study compares a brain maturation of subjects with good and poor - four years outward. These subjects and others also participate in studies of the genetics of ADHD using family association and affected-sibling designs in collaboration with a multi-center multi-institute consortium. Neurophysiological approaches have investigated the usefulness of eye movement tasks in ADHD. Girls with ADHD show executive function abonormalities on Delayed Response and Go-No Go eye movement tasks, but substantial practice effects may limit task utility. Diffsion tensor imaging studies are examining white matter abnormalities in discordant ADHD monozgotic twins.